This invention relates to an outboard motor and more particularly to an improved protective cowling therefor.
As is well known, outboard motors generally include a power head that consists of a powering internal combustion engine and a surrounding protective cowling. The cowling is provided around the engine so as to provide a neater appearance and also to protect the engine from foreign materials. Of course, it is necessary that the protective cowling have an inlet opening arrangement so that air for combustion of the engine can enter the protective cowling in adequate quantities to maintain the desired maximum engine output. This gives rise to a number of problems.
First, it is important that the cowling inlet opening be positioned and configured in such a way that there can be adequate air flow to the engine so as to provide the desired output of the engine. However, because of the operation in close proximity to large bodies of water and since the water frequently may be sprayed upwardly by the operation of the watercraft into proximity with the inlet opening, there must be insurance against the ingestion of water through the inlet opening into the interior of the protective cowling where it could possibly damage the engine. Thus, arrangements have been provided that will assist in separating the water from the inducted air to prevent the water from entering into the interior of the protective cowling.
Although the goal is simple, the achievement of this goal is much more complicated. It is of course desirable to maintain a slim profile for the power head and also so as to avoid undue height. Thus, the space available for this air induction and water separation is quite restricted.
It has been proposed to employ various arrangements wherein a labyrinth type air flow path is provided between the atmospheric air inlet opening and the opening in the protective cowling that permits the air to enter the interior of the protective cowling. Such air flow paths, however, provide a reduced flow area and can restrict the output of the engine.
Also, there is a problem in connection with the draining of the separated water from the inducted air so that the water does not reenter the air stream and pass into the interior of the protective cowling. Generally, the air inlet openings are provided at the rear of the cowling and the drain passages for the return of the separated water from the cowling area is in proximity to the inlet opening. This provides significant problems in that the air flow may tend to sweep the separated water back into the interior of the protective cowling.
It is, therefore, a principal object of this invention to provide an improved air inlet device for the protective cowling of an outboard motor.
It is a further object of this invention to provide an air inlet arrangement or an outboard motor protective cowling that provides substantial separation between the air inlet opening for the induction system and the water drain for draining separated water from the inducted air before it passes into the interior of the protective cowling and into proximity with the engine.
In addition to the issue of avoiding restrictions in air flow, it is also desirable if the induction system provided in the cowling can provide an expansion chamber area. This will assist in not only maintaining good induction properties but also can assist in silencing the inducted air. However, if the expansion chamber volume is increased, then the exterior configuration of the protective cowling can be unduly bulky.
It is, therefore, a still further object of this invention to provide an improved intake arrangement for the protective cowling of an outboard motor that will provide sufficient expansion volume and will do this in such a way that the overall size of the cowling is not increased.
Because of the demand for larger and larger power outputs for outboard motors, the number of cylinders employed in the engine is substantially increasing. This gives rise to further expansion in the overall size of the protective cowling and also means that there is a greater engine displacement and hence more air is required for engine operation.
Furthermore, in order to improve the performance of the engine, it has been proposed to utilize such performance improving features like fuel injection systems. The fuel injection system may also be of the direct cylinder type which can provide further enhancements of engine operation. However, the use of fuel injection systems adds to the number of components that are contained within the protective cowling and this is further complicated when direct injection systems are employed.
The direct injection systems require not only a greater number of fuel injectors but also more complicated supply systems. The supply system becomes more complicated because higher pressures must be generated in direct injected engines and thus additional and high-pressure positively driven fuel pumps may become necessary.
All of these components are generally positioned in the area of the protective cowling that is contiguous to the air inlet area. This means that these delicate and sensitive components of the engine and specifically of its fuel injection system may become exposed to inducted water. Thus, the aforenoted problems with respect to water separation are even more important in connection with outboard motors having fuel injection systems and particularly direct injection systems.
Furthermore, the positioning of the inlet arrangement utilized with conventional outboard motor protective cowlings is such that the air is inducted in an area in close proximity to where many of the fuel injection system components are located. Thus, it is highly likely that any water in the inducted air will contact these components and cause potential problems.
It is, therefore, a still further principal object of this invention to provide an improved protective cowling arrangement and air inlet arrangement therefor that is particularly adapted for use with outboard motors having fuel injection and particularly direct cylinder injection.
The problems in conjunction with the prior art type of protective cowling arrangements can be best understood by reference to FIGS. 1-3. These figures show the main cowling member, indicated generally by the reference numeral 21, of the type utilized with conventional prior art type of constructions. The main cowling member 21 is comprised primarily of two main components both of which may be formed from a suitable material such as a molded fiberglass reinforced resin or the like. These two components of the main cowling member 21 are detachably connected to a tray which is not shown and which with the main cowling member 21 encircles the powering internal combustion engine, which is not illustrated in these figures.
The main cowling member 21 is comprised of a main cowling portion 22 that has a generally inverted cup-shaped configuration and which defines an internal cavity 23 in which the associated engine is contained. The main cowling member 22 has an upper surface 24 that is formed with an indented portion 25 at the rear end thereof which is covered and enclosed by a closure member 26 that is connected to the main cowling member 22 in a suitable manner, such as by means of fasteners 27. An upstanding inlet opening neck 28 that defines an internal passage 29 that communicates the chamber formed by the indented area 25 and the closure member 26 with the interior 23 of the protective cowling member 21.
The closure member 26 is provided, as best seen in FIG. 3, with a plurality of slotted openings 31 formed in the rearward portion thereof that permit air to flow into the indented area 25 as seen by the arrows A in FIGS. 1 and 2. This air then flows around the inlet neck 28 and downwardly through the opening 29 into the cowling interior 23 for induction into the engine for combustion.
By utilizing the tuning neck 28 and the somewhat circuitous air flow path, water will tend to separate from the inducted air. This water then is drained down into a drain recess 32 that is formed at the rear of an upstanding rear surface 33 of the main cowling member 22. The closure member 26 has a skirt portion 34 that partially encloses this recess 32 and defines a lower drain slot 35 through which water is intended to drain. By utilizing the recess 32 and slot 35, the water return may be separated from the air inlet openings 31 so as to attempt to minimize the amount of water that can reenter the inducted air.
It will be seen that the area adjacent the recess 27 in the main cowling member 22 and the closure 26 defines a small gap 36 which is necessary to accommodate manufacturing variations and the like. This, however, gives rise to an area where air can seep into the interior as indicated by the arrows AL in FIG. 1 and tend to bypass the separation system and flow directly into the air outlet opening 29.
It is, therefore, a further object of this invention to provide an improved cowling construction for an outboard motor wherein water is separated from air that may leak through gaps in the cowling and drained away from the air inlet.
Also, the air outlet opening 29 is disposed immediately above the engine and with certain type engines, as will become apparent when the preferred embodiment of the invention is described, this is in proximity to many components of the fuel injection system that should be protected from water.
One way that this protection can be improved is by raising the height of the cowling in this area as shown in phantom in FIG. 2. This, however, provides not only an obstruction to visibility but provides a less than pleasing appearance to the outboard motor.
Also, it should be readily apparent from viewing FIGS. 1 and 2 that the volume of the chamber formed by the indented area 26 is quite restricted and hence there can be a restriction to air flow. Also this small volume gives rise to relatively short flow paths that makes the water separation more difficult.
Thus, it is believed that the description of FIGS. 1-3 emphasizes the disadvantages of the prior art type of construction, as aforementioned and thus makes the objects of the invention as have already been described more desirable.